beran earms

Can anyone give me a simple explanation of this? What does it stand for, what are the benefits, negatives etc. I see all kinds of tid bits of info here and there, but nothing in one place, to get right to it. This may seem like a goofy request but I'm not finding what I need. Thanks again.

FredR

Rear muffler bypass. You remove the heavy final stage and replace with a straight through pipe. it sounds better, is lighter but claims of additional power I do not buy into- certainly nothing you can feel.

Regards

Fred

beran earms

perfect! But one more ? I know that sound is a personal thing but how can you describe it, at different rpm etc. Is it at all annoying? I have made mods on other vehicles some sounded awesome while others were quickly discarded

joejoe

I would call it a more 'throaty' sound. At idle there seems to be more of a 'burble'. Hard acceleration makes it sing. Both my '86.5's had them. I changed the grey car back to stock to have one that was quiet. I enjoy both.

FredR

I think Joe's description is about as good a way off describing it as one can. Some like it some do not- a personal type of thing. I think some associate the increased sound level with increased power but I doubt anyone has ever detected performance improvement on a stop watch.

The X pipe is a different matter- there is a noticeable improvement performance wise but in my case I also noticed a somewhat annoying drone around the point where the flappy valve opens others have noted the same.

Rgds

Fred

beran earms

The drone is what worries me. I did an exhaust mod on something and it sounded so good in the garage, around town and wide open. Then I went on a road trip on the highway and could not stand it, about 2200 rpm for long duration I was ready to jump out. What about X with RMB?

FredR

That is what I have together with a custom bullet muffler in the centre section and it drones around 3600 to 3900 rpm. Even the amount of drone varies [with load factor I presume].

Rgds

Fred

davek9

Your lucky on an 86.5 (and S4) it is a simple bolt on, however the two are different shapes.

Make sure you get one made for an 86.5, unbolt and remover your rear muffler and replace it with the (RMB) it's not really a bypass, it's a muffler replacement

If you don't like it, resell it, only takes less then 30 mins to R&R including clean up

You most likely will keep it

PorKen

RMBs sound great for about 1/2 hour if you don't have cats. They do save a lot of weight, though!


'78-'86.5 rear mufflers are restrictive. They are actual mufflers in that the pipes dead-end in the case and the exhaust is forced through holes in the pipes. (Probably not a big deal but '86.5 dual exhaust pipes are larger than the muffler inlet pipes, too.)

S4, GT, GTS rear mufflers are resonators. They go straight though. I haven't seen a difference on the dyno with our without.

Side note: mids are resonators on all years. Even the big '86.5-'87/GTS type.

martinss

A number of people have posted videos of RMB sound, but mostly at rest. Search Youtube for '928 RMB'

Bill Ball

The stock exhaust on my 89 was very quiet. Installing an RMB produced a fairly typical V-8 muscle car note. I liked it. Adding an X-pipe (essentially the Louie Ott type sold by Roger), did give me a dyno documented +30HP but created the 2200 RPM drone mentioned already, right in the middle of the cruise range. Kind of annoying inside the passenger compartment. Despite the power gain, the x-pipe is gone, but I still have the RMB. I can live with that. As a side note, I've always liked the RMB sound, but when I moved into a rather sedate retirement community, the sound was a bit much for my neighbors. I swapped in the 87 large resonator sections. Still have a decent muscle car sound but the 87 resonators did quiet the overall noise level.

FredR

Does anyone happen to know if the stock resonators actually work? As I understand they are intended to cancel out certain engine frequencies [what ones I have no clue].

Given I run without one, have a Bullett muffler in the central section and nothing else in the system I have often wondered what might be going on inside the exhaust system. Louie recommended thi system for me some 10+ years ago and have run with it ever since.

I suspect I would not get on too well with Bill's neighbours! Fortunately the Oman Police seem to like the sound of my car when it goes for annual inspection - given it is an old car and a Porsche [last of class on the streets here I suspect] they do not give me any hassle [to date].

Rgds

Fred

NC928S4

The RMB as stated previously brings out more of a muscle car rumble. It's not overbearing but very noticeable and brings a certain stupid adolescent grin to me and others watching me smile stupidly.

It's not for everyone but the car is my daily drive mostly around town and back and forth to airport and I enjoy the audible feedback while driving. I'm lucky if I drive it 5,000 miles/year.

I'm currently saving up for X-pipe and CATs because I want the added HP.

Your call

jwyatt8171

When I bought my car almost 2 years ago it had a RMB. I really like the sound of it. Having the bug to fix what isn't broke I bought a cat-less X pipe from 928sRus.com .

At first I thought it was great when I first fired it up, but quickly realized people here knew what they were talking about. With various tools scattered about in the back of the car I took off...EVERYTHING, I mean EVERYTHING in the car rattled between 2200-2600 RPM. The sound outside is obnoxiously loud IMO. I didn't realize how loud until I took off from a stop light, and other cars were coming the opposite direction, and as I passed them it startled me how loud the exhaust sound was bouncing off the other cars...think NASCAR loud!

To remedy this I can either put the stock cats back in place, or go full 2.5" exhaust with mufflers. I think this is the exhaust most claim good result from. I will probably full 2.5" because I can. haha

FredR

If your 90 S4 has those stock, pissy little resonators then I would think you will be public enemy number 1 never mind a target for Bill's "retirement community hit men". Indeed I suspect it would be darn right uncomfortable in the cabin.

As I am concerned one either fits the x-pipe and retain everything else or do as I did and modify the central section to introduce a sensible degree of noise attenuation. I like my exhaust setup but at times I feel it transmits an element of "boy racer". You would think that at 63 years young I might have matured a bit more - however I believe in the mantra "think young stay young"!

Regarding noise I do not think one ever appreciates just how the car sounds until you hear someone else driving it - a lot to do with the Doppler effect I suspect. My wife has zero interest in the 928 [and cars in general] but some years ago she was at a local supermarket with our daughters when she heard a car accelerating hard on the highway- she said to the girls "that sounds like your Dad's car"- it was! Exclusivity- you cannot beat it!

Rgds

Fred